Indexing mechanism



0d. 25, 1938. A. H. ,RCUTT ET AL j 2,134,234

Oct. 25, n A' H- ORCUTT ET AL Y INDEXINGr` MECHANISM Filed Nov. 8, 1937 3 Sheets-Sheet 2 Get. 25, 1938. l A H, ORCUTT ET AL 2,134,234 i l INDEXING MEOHANISM Filed Nov.- 8, 1957 :5 Sheets-Sheet :5

Figga Patented Oct. 25, 1938 UNITED STATES INDEXING MCH NT"`siv`t Arthur iiiehoek oieiiit ana Richard John nur lows, Birmingham,

England, assign's'- to The Gear `'Grriiding Company Limited,irminghfm,

` England Aiilieaiioii November s, 1937, seiiai no, 173,5@7'

In Great Britain December 5, 1936 4 claims. (o1. 51-2165 1 tilfan'sv'erse.sciievvv threadedb-e througlfiv which I i This invention has' for its object to provide an improved indexing mechanism adapted for more particularly on gear grinding'` machinesI but applicate also to otneranaicgus machines in Which it is required to impart intermittent anglilar movements to a vvork piece for presenting different aspects of the latter to a grinding or cutting tool. y l o l The invention comprises the combination of an indexing plate provided with teeth vor notches, an oscillatory actuating pawl adapted by en` gagement with the teeth or notches Yto impart intermittent and unidirectional angular move-v ments to the plate, a positioning pawl adapted by zzo-operation with the teeth or notches of the plate to determine its stationary positions, afriction brake acting in opposition to the movements oi the plate, and `resilient meansvfor opposing rotationrof the brake, the arrangement being such that during each angular movement of the plate under the action of ,Y theactuating pawl energy is stored in the said e e o resilient means, and at the completion er each such movement of the plate (Which isslightly in excess ot the movement refquired) the said energy is utilized to impart a small butsufncient -retilrn movement to the plate to bring a ace of the appropriate tooth or notch into abutment with the positioning pawl.

In the accompanying sheets of explanatory diavvings: e

JFigures l and 2 n are respectively a part secenal'front elevation and a part sectional plan of indexing mechanism constructed in accordance`vvith`the invention for a gear grinding vor other machine. Y Y

Figure 3 is a section on the line 3 3 of Figure n carrying the invention into effect as shown, We mounten the work-spindle an indexing plate b havingrits periphery formed with suitably spaced teeth c each having a radial faced, the spacing of the teeth c corresponding to the intermittent and unidirectional angular movements required to be given to the plate b and Work-spindle d forindexing the work piece (not shown). The plate b is actuated by a pawl e carried on an oscillatory arm f adapted to be osoillated about an aXis'CoaXial With that of the plate b b y any convenient crank 'or other mechanis'm which is appropriately ctn-ordinated with the other movements of the machine. In the eX- arnple shown, the arm f is mounted on a sleeve f1 surroundinga boss b1 on the plate b. Also the oiiter end of the armj carries a pivotal bearing gin which isl journalled a member h, having a passes a complementary s'erew threaded end of a horizontal reciprocatoiy r'od z'. The other end of the rod z' is aise :screw threaded and carriesfa pair of nuts i; rjiir'tner the iatter Yend of the rod i passes freely-`- through a transverse bore in a memberflc, and the nuts 7' adjustably secureithe rod to ,this member bya'cting on opposite sides of the latter. The member It is journalledin a pivotal bearing carried byla member n' which is adapted toftransn'iit reoiprcatory movements to the rod i from a crank o n aY shaft p driven from any convenient part of the machine-` The member n serves as a crankp'inand is adjnstably (SlOt l fll'rld longitudise'eur'ii by nous q iii a;

nally in the crank By appropriately adjusting I the plositioinlo'fY the member n onthe crank o, the amplltlid'e ofthe movements imparted to the rod i bythe member it and, consequently, vto the arm f by the rod i', can be varied as required. The pawl e' isl'iyotd onvthe arm f adjacent tothe outerY end' of the latter, and is controlled by a spring` l in the forni of a strip attached at one end to the` rear end Of the pavvl, the other end of the strip being arranged to abut against a peg 'r on the arn f. lThe pav'vl e` is .adapted to abut against the radial face d 'f each tooth c in succession, andthe amount of Vangularmovement given to the plate Zi by the pawl in each operative `movenfient of the arm f is slightly in excess of the motion actually required. Adjacent to the actuating'pawl e thereis pivoted on any convenient stationary parasuch as, the casing t of the mechanism, a positioning pawl u the free end of which is also adapted to abut against the radial fae d of each to'oth c in turn. The positioning 'pavvl u falls inte position byits own Weight, or it maybe' aided by sition of this pavvl being detrmindby an adjustable abutment in thel orm of a screw v secured to the casing t, the outer e'nd of the paWl u being adapted to abut against the head ofthe screw v as shown. rWhile the plate b is'being moved relatively to the positioning pawl uthe latter rides idly over the rear face of each tooth @which face may be of any convenient inclined or other shape.

@O n the Work-spindle a is arranged a brake anim w, and ihisj'isjefribfaced by a pair' of brake shoesa'f: arranged at opposite' sides of the drum.

afspring, the operative po- At onepair of adjacent ends the brake shoes are pivoted to and interconnected by attachment pieces g/,and at the''tlier pair of adjacent ends the Ici-rake shoes are formed or provided with member.

towards each other by a spring 2 on a screw 3 to oppose rotation of the plate b, rotation of thej shoes is opposed by a spring supported stop. In the example shown, this stop has the form of a collar 4 slidably mounted on a rod 5 and adapted to abut, under the action of a spring 6, against an abutment piece 'l which is journalled` in a bracket 8 secured to one of the lugs z. The rod 5 is supported at one end by a bearing member 9 extending from the casing vt, and the Yportion of the rod remote from this end is reduced.

VThis reduced portion of the rod 5 carries the collar 4 and passes freely through' a transverse hole in the abutment piece 1I, the spring 6 being arranged on the rod between the collar and a nut I0 in screw thread engagement with the rod. By adjusting the nut l0 the pressure exerted by the spring Bron the collar 4 can be varied as required. A plate IB detachably secured to the bearing 9 co-acts with a at face of the nut I0 to retain the latter in its adjusted position.

During each angular movement of the plate b under the action of the pawl e and against the action ofthe brake shoes these shoes (because they tend to rotate with the drum w) Compress the spring 6 by the co-operation of the abutment piece 'I and collar 4, and thereby cause energy to be stored inthe springB. After the actuating pawl e has ceased to exert its effort on the plate b, and during the initial part of the return movement of this pawl, the spring 6 by its action on the abutment piece 'I imparts a small return movement to the plate b, thereby bringing the radial face d of the operative tooth c gently into contactwith the end of the positioning pawl u for accurately determining the stationary position of the plate b.

For enabling the plate b to be adjusted angularly on the work-spindle a we arrange the plate so that opposite ends of its boss b1 abut respectively against a shoulder a1 on the spindle and a retaining member I1 detachably secured on the end of the spindle by a clamping screw I8 passing through ar split portion of the retaining A key I9 prevents rotation of the retaining member I'I relatively to the spindle a., but permits this member to be removed from the spindle when the clamping screw I8 is released. Formed on the retaining member I1 is a bifurcated part 2i! which carries adjusting screws 2I adapted toact on opposite sides of a rod 22 extending from the adjacent side of the plate b. By appropriately manipulating the screws 2| the angular position of the plate b on the spindle a can be varied as required. For separating the brake'shoes a: to permit free rotation of the spindle a and plate b during testing and like operations, a rod II is adapted at its inner end to be screwed through a bore I2 in one of the lugs z, and to exert pressure against the adjacent side of the other of these lugs, vthe outer end of this rod, which extends through an opening I3 in the casing t being provided with an operating handle I4.

The invention is especially suited for indexing mechanisms used with heavy Work; pieces where inertia effects are likely to be large, and

by the invention We are able to effect rapid indexing of such workpieces without shock in a very simple and convenient manner.

The invention is not limited to the example described, as subordinate mechanical details may be varied to suit different requirements. Thus, instead of providing teeth on the periphery of the indexing plate, this plate may be formed with peripheral notches for co-operating with the pawls, and preferably one face 0f each notch is y radial to the axis of the plate.

Having thus described our invention what we claimas new and desire to secure by Letters Patent Visz-- l. Indexing mechanism for machine tools, comprising the combination of a rotatable indexing plate provided with abutment surfaces, an oscillatory actuating pawl adapted by engagement with said abutment surfaces to impart intermittent and unidirectional angular movements to said plate, a positioning pawl adapted by cooperation with said abutment `surfaces to determine the stationary positions of said plate, a friction brake having interacting parts formed by a member rigid with said plate and gripping means carried by said member, and resilient means co-operating with said gripping means so that, during each of the angular movements imparted to said plate by said actuating pawl, said resilient means acquires energy which at the completion of each of said angular movements of the plate is utilized to impartA a small but sufficient return movement to said plate through said gripping means to bring the appropriate abutment surface of said plate into contact with said positioning pawl.

2. Indexing mechanism for machine tools, comprising the combination of a rotatable vindexing plate provided with abutment surfaces, an actuating pawl adapted by engagement with said abutment surfaces to impart intermittent and unidirectional angular movements to said plate, an arm carrying said actuating pawl and adapted to be oscillated about an axis co-axial with that of said plate, a positioning pawl adapted by co-operation with said abutment surfaces to determine the stationary positions of said plate, a brake'drum coaxial and rigid with said plate, gripping means carried by and co-oper'ating with said brake drum, and a spring-supported stop co-operating withvthe said gripping means so that, during each of the angular movements imparted to said plate by said actuating pawl, said resilient means lacquires energy which at the completion of each of said angular movements of the plate is utilized to impart a small but sucient return movement to said plate through saidV gripping means to bring the appropriate abutment surface of said plate into contact with said positioning pawl. i

3. Indexing mechanism for machine'tools, comprising-thecombination of a rotatable indexing plateprovided with abutment surfaces, an oscillatory actuating pawl adapted by engagement with said abutment surfaces to impart intermittent and unidirectional angular movements to said plate, a positioning pawl adapted by co-operation with said abutment surfaces to determine the stationary positions of said plate, a brake drum coaxial and rigid with said plate, a pair of interconnected brake shoes carried by and embracing cpposite sides respectively of said drum, resilientk means urging said brake shoes into contact with said drum, and a spring-supported stop co-operating with one of said brake shoes so that,

during each of the angular movements imparted to said plate by said actuating pawl, said stop acquires energy which at the completion of each of said angular movements is utilized to impart a small but sufficient return movement to said plate through said gripping means to bring `the appropriate abutment surface of said plate into contact with said positioning pawl.

4. Indexing mechanism as claimed in claim 3,

l0 in which the spring-supported stop comprises the combination of a rod, a collar slidably mounted on said rod and adapted to co-act with one of the brake shoes, a spring mounted on said rod and abutting at one end against said collar, and an adjustable nut in screw thread engagement with said rod and adapted to act on the oposite end of said spring for regulating the pressure exerted by the latter on said collar.

ARTHUR HITCHCOCK ORCU'I'I'.

RICHARD JOHN BULLOWS. 

